[systemd-devel] [PATCH] util: fix strict aliasing violations in use of struct inotify_event v5
Lennart Poettering
lennart at poettering.net
Tue Dec 23 14:14:37 PST 2014
On Tue, 23.12.14 13:47, Shawn Paul Landden (shawn at churchofgit.com) wrote:
> There is alot of cleanup that will have to happen to turn on
> -fstrict-aliasing, but I think our code should be "correct" to the
> rule.
Applied with some minor changes! (we try to use _t only for things
that actually feel like types, you'd pass around via call-by-value,
not call-by-ref...)
Thanks!
> ---
> src/core/mount.c | 4 ++--
> src/core/path.c | 4 ++--
> src/journal/sd-journal.c | 4 ++--
> src/shared/util.c | 5 ++---
> src/shared/util.h | 10 ++++++++--
> src/udev/udevd.c | 4 ++--
> 6 files changed, 18 insertions(+), 13 deletions(-)
>
> diff --git a/src/core/mount.c b/src/core/mount.c
> index f8731bb..18ee2a0 100644
> --- a/src/core/mount.c
> +++ b/src/core/mount.c
> @@ -1701,11 +1701,11 @@ static int mount_dispatch_io(sd_event_source *source, int fd, uint32_t revents,
> * internal behaviour of libmount here. */
>
> for (;;) {
> - uint8_t buffer[INOTIFY_EVENT_MAX] _alignas_(struct inotify_event);
> + inotify_event_buffer_t buffer;
> struct inotify_event *e;
> ssize_t l;
>
> - l = read(fd, buffer, sizeof(buffer));
> + l = read(fd, buffer.raw, sizeof(buffer.raw));
> if (l < 0) {
> if (errno == EAGAIN || errno == EINTR)
> break;
> diff --git a/src/core/path.c b/src/core/path.c
> index 656ed69..bc34f66 100644
> --- a/src/core/path.c
> +++ b/src/core/path.c
> @@ -157,7 +157,7 @@ void path_spec_unwatch(PathSpec *s) {
> }
>
> int path_spec_fd_event(PathSpec *s, uint32_t revents) {
> - uint8_t buffer[INOTIFY_EVENT_MAX] _alignas_(struct inotify_event);
> + inotify_event_buffer_t buffer;
> struct inotify_event *e;
> ssize_t l;
> int r = 0;
> @@ -167,7 +167,7 @@ int path_spec_fd_event(PathSpec *s, uint32_t revents) {
> return -EINVAL;
> }
>
> - l = read(s->inotify_fd, buffer, sizeof(buffer));
> + l = read(s->inotify_fd, buffer.raw, sizeof(buffer.raw));
> if (l < 0) {
> if (errno == EAGAIN || errno == EINTR)
> return 0;
> diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c
> index d46dc3c..5f65116 100644
> --- a/src/journal/sd-journal.c
> +++ b/src/journal/sd-journal.c
> @@ -2188,11 +2188,11 @@ _public_ int sd_journal_process(sd_journal *j) {
> j->last_process_usec = now(CLOCK_MONOTONIC);
>
> for (;;) {
> - uint8_t buffer[INOTIFY_EVENT_MAX] _alignas_(struct inotify_event);
> + inotify_event_buffer_t buffer;
> struct inotify_event *e;
> ssize_t l;
>
> - l = read(j->inotify_fd, buffer, sizeof(buffer));
> + l = read(j->inotify_fd, buffer.raw, sizeof(buffer.raw));
> if (l < 0) {
> if (errno == EAGAIN || errno == EINTR)
> return got_something ? determine_change(j) : SD_JOURNAL_NOP;
> diff --git a/src/shared/util.c b/src/shared/util.c
> index 06b6077..2fbcdab 100644
> --- a/src/shared/util.c
> +++ b/src/shared/util.c
> @@ -39,7 +39,6 @@
> #include <linux/tiocl.h>
> #include <termios.h>
> #include <stdarg.h>
> -#include <sys/inotify.h>
> #include <sys/poll.h>
> #include <ctype.h>
> #include <sys/prctl.h>
> @@ -2106,7 +2105,7 @@ int acquire_terminal(
> assert(notify >= 0);
>
> for (;;) {
> - uint8_t buffer[INOTIFY_EVENT_MAX] _alignas_(struct inotify_event);
> + inotify_event_buffer_t buffer;
> struct inotify_event *e;
> ssize_t l;
>
> @@ -2129,7 +2128,7 @@ int acquire_terminal(
> }
> }
>
> - l = read(notify, buffer, sizeof(buffer));
> + l = read(notify, buffer.raw, sizeof(buffer.raw));
> if (l < 0) {
> if (errno == EINTR || errno == EAGAIN)
> continue;
> diff --git a/src/shared/util.h b/src/shared/util.h
> index 1804b8c..e9af32a 100644
> --- a/src/shared/util.h
> +++ b/src/shared/util.h
> @@ -42,6 +42,7 @@
> #include <locale.h>
> #include <mntent.h>
> #include <sys/socket.h>
> +#include <sys/inotify.h>
>
> #if SIZEOF_PID_T == 4
> # define PID_FMT "%" PRIu32
> @@ -1047,8 +1048,13 @@ int sethostname_idempotent(const char *s);
> #define INOTIFY_EVENT_MAX (sizeof(struct inotify_event) + NAME_MAX + 1)
>
> #define FOREACH_INOTIFY_EVENT(e, buffer, sz) \
> - for ((e) = (struct inotify_event*) (buffer); \
> - (uint8_t*) (e) < (uint8_t*) (buffer) + (sz); \
> + for ((e) = (struct inotify_event*) (&buffer.ev); \
> + (uint8_t*) (e) < (uint8_t*) (buffer.raw) + (sz); \
> (e) = (struct inotify_event*) ((uint8_t*) (e) + sizeof(struct inotify_event) + (e)->len))
>
> +typedef union {
> + struct inotify_event ev;
> + uint8_t raw[INOTIFY_EVENT_MAX];
> +} inotify_event_buffer_t;
> +
> #define laccess(path, mode) faccessat(AT_FDCWD, (path), (mode), AT_SYMLINK_NOFOLLOW)
> diff --git a/src/udev/udevd.c b/src/udev/udevd.c
> index 8bec03e..b07dff8 100644
> --- a/src/udev/udevd.c
> +++ b/src/udev/udevd.c
> @@ -816,11 +816,11 @@ static int synthesize_change(struct udev_device *dev) {
> }
>
> static int handle_inotify(struct udev *udev) {
> - uint8_t buffer[INOTIFY_EVENT_MAX] _alignas_(struct inotify_event);
> + inotify_event_buffer_t buffer;
> struct inotify_event *e;
> ssize_t l;
>
> - l = read(fd_inotify, buffer, sizeof(buffer));
> + l = read(fd_inotify, buffer.raw, sizeof(buffer.raw));
> if (l < 0) {
> if (errno == EAGAIN || errno == EINTR)
> return 0;
> --
> 2.1.0
>
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> systemd-devel at lists.freedesktop.org
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Lennart
--
Lennart Poettering, Red Hat
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